At my old job, I used to surf the web a lot. Now, working for myself, I still do that sometimes. I usually spend a few minutes here and there on Eden during the workday. If I need to "reset my brain", I play a short video game. If I'm falling asleep, I'll get up and stretch. Typically, I spend 45 minutes on work, and then maybe 5-10 minutes "goofing off". I think I get more done that way than I would if I forced myself to work without such breaks.